When drilling wells into the earth, a string of drill pipe is rotated and driven into the earth to form the hole or well. Water is typically flowed into the well during drilling, with the water and removed earthen material flowing upwardly around or within the rotating drill pipe and outwardly of the bore hole being drilled.
One example prior art drilling assembly uses stabilizers and reamer arm assemblies aft (up-hole) of the cutting head apparatus. For example, a cutting head apparatus is provided at the end of a drill string assembly and is configured to cut into earthen material as the cutting head apparatus is rotated. A drive shaft extends aft of and is configured to rotate the cutting head apparatus as driven by the drill string assembly. The drive shaft is rotatably received between a pair of stabilizer assemblies received proximate the cutting head apparatus. The stabilizer assemblies include a plurality of radially projecting arms respectively having pairs of solid rubber tires mounted for rotation about horizontal axes at the outer ends of the arms, and which bear against the sidewalls of the bore hole. The outermost diameter extent of the stabilizers is slightly greater than the outermost diameter of the cutting head such that the stabilizer tires compress and bear tightly against the bore hole aft of the cutter head as the drilling assembly is advanced into the earth. The drive shaft is rotatably received through the stabilizer assemblies which essentially act as bearings for restraining the cutting head apparatus from appreciable lateral movement as it is advanced into the earth.
A plurality of reamer arm assemblies is received between the pair of stabilizers and mount to the drive shaft for rotation therewith. The individual reamer arms have a pair of cutters received at the radially outer ends thereof. Opposing pairs of reamer arm assemblies have an outermost diameter extent which is slightly less than the outermost diameter of the cutting head apparatus. An intended function of the reamers is to follow behind the cutting head to cut a smooth finish to the bore hole by carving off undulations that might occur in the path of cutting through the rock/earthen material, and facilitate the cutting apparatus going straight.
At the conclusion of drilling, the entire drilling assembly is of course removed from the bore hole. The reamer arm assemblies, being in close proximity to the sidewalls of the bore hole, on occasion engage such sidewalls, causing the entire apparatus to essentially get “stuck” in the bore hole. Such can require lowering of the drilling assembly slightly within the borehole and rotating it slightly prior to again attempting to extract the drilling assemble from the bore hole. Such is, of course, time consuming and may cause damage to the cutters on the reamer arm assemblies.
While the invention was motivated in addressing the above identified issues, it is in no way so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents.